<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta
      name="viewport"
      content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"
    />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>Document</title>
    <style>
      body,
      html {
        height: 100%;
        width: 100%;
        padding: 0;
        margin: 0;
      }
      .container {
        height: 2000px;
        background-color: red;
      }
      .top {
        height: 200px;
        width: 100%;
        background-color: green;
        position: fixed;
        z-index: 10;
      }
    </style>
  </head>
  <body>
    <div class="container">
      <div class="top">
        <div>
          <h1>hello</h1>
        </div>
      </div>
    </div>
  </body>
</html>
